Not a permanent solution, but any metal shop or motorcycle/auto custom shop in your area might have a wet metal cutting machine, or laser which would help you for a simple fix. The prices are pretty low especially if you show up in person. Certain Napa Auto parts stores can also do it (along with sand blasting) for very little $$$.
Buying your own hole saw, or set, sets you up for life though might be too much $$$ for 1 cut.